Personally I prefer symlinks because it makes it easy to tell what files I have directly under source control. But hard links should work fine and should mean that even if Dropbox mysteriously decides to delete your files from your ~/Dropbox/ directory you will still have a local copy of them and be able to use your system without interruption.

And how do you imagine that it would happen that Dropbox would randomly trash the contents of your files? And if it was that buggy why the bug be limited to just the files in your ~/Dropbox/? By that argument you might as well say that it could trash any file owned by your user. And if you believe Dropbox to be likely to have such serious bugs, why just Dropbox and not other software you are using? For example Chromium or Firefox? Or any other piece of software?

Seems less like a serious concern and more like trying to think up any imaginable thing that could conceivably go wrong no matter how unlikely.

Lots of ways. Suppose they tried to implement a 3-way merge system (a la git) to resolve conflicts in your synced files. It's easy to see that going terribly wrong if they implement it incorrectly.

It's proprietary software as a service. That means they could conceivably make a breaking change like that without even notifying you, the user, and cause data loss.

Scenario- win7, win10, mac, phone had a folder called “admin” with multiple sub folders. Turning off syncing on a sub folder on one of these ended up deleting the folder and all it’s contents on all the machines. Renaming or moving folders has also resulted in unexpected deletes.

OneDrive is not Dropbox, but it reminded me not to do this with important files regardless that Dropbox has been pretty solid for 10+ years.

I’m back to rsync from “source” and not using OneDrive for workflow.